# Help me understand blood types please. **URL:** \ **Category:** Factual Questions\ **Created:** [May 17, 2004, 2:43pm UTC](https://boards.straightdope.com/t/help-me-understand-blood-types-please/245610 "2004-05-17T14:43:42Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![The\_Chao\_Goes\_Mu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_chao_goes_mu/32/3191_2.png) [@The\_Chao\_Goes\_Mu](https://boards.straightdope.com/u/The_Chao_Goes_Mu)\ **Post date:** [May 17, 2004, 2:43pm UTC](https://boards.straightdope.com/t/help-me-understand-blood-types-please/245610/1 "2004-05-17T14:43:42Z")
It’s been a while since i’ve taken an anatomy class and now I can’t remember all of the blood types and the order in which they were most common to the least common. Also, what effect, if any, does a particular blood type have on a person? For example, a friend was telling me that people with Type A blood have a higher likelihood of certain food allergies such as tomatoes. Is this even remotely true? I’m so confused! 😕 Thanks! ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [May 17, 2004, 3:04pm UTC](https://boards.straightdope.com/t/help-me-understand-blood-types-please/245610/2 "2004-05-17T15:04:03Z")
[First Google hit](http://www.biology.arizona.edu/human_bio/problem_sets/blood_types/Intro.html) ---
**Author:** ![One\_And\_Only\_Wanderers](https://avatars.discourse-cdn.com/v4/letter/o/838e76/32.png) [@One\_And\_Only\_Wanderers](https://boards.straightdope.com/u/One_And_Only_Wanderers)\ **Post date:** [May 17, 2004, 3:09pm UTC](https://boards.straightdope.com/t/help-me-understand-blood-types-please/245610/3 "2004-05-17T15:09:50Z")
Type A blood has the A antigen (well duh! 😉 ) Type B blood has the B antigen Type AB has both the A antigen and the B antigen Type O has neither antigen if the sample is rhesus positive then it contains something (a protein) that is also found in the rhesus monkey, if it is negative then it doesn’t. People with type AB can be given blood from any group (universal acceptors) People with Type O blood can only be given type O, but their blood can be given to anyone (Universal donors) don’t know anything about certain blood types causing a predilection towards allergies etc. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [May 17, 2004, 5:20pm UTC](https://boards.straightdope.com/t/help-me-understand-blood-types-please/245610/4 "2004-05-17T17:20:14Z")
There are many different kinds of blood types, but most people think of the ABO system, which ultimately describes which chains of sugar molecules you have sticking out on the surface of your red blood cells. There’s a chain we’ve labelled “A” and a chain we’ve labelled “B”. If you have both of them, you’re AB. If you have neither, you’re “O”. This food allergy crap is just that. It’s the latest pseudoscience claptrap that’s been floating around to help justify the sale of fraudulant diet programs. There’s absolutely no evidence to support it. It’s right up there with homeopathy and pain-relieving copper bracelets. The only affect blood type has on a person is to determine which blood types you’ll react negatively to. Well, the Rh factor can also cause problems during pregnancy, so I guess that’s two affects. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [May 17, 2004, 6:04pm UTC](https://boards.straightdope.com/t/help-me-understand-blood-types-please/245610/5 "2004-05-17T18:04:18Z")
There are [46](http://en.wikipedia.org/wiki/Blood_Types) systems of typing blood antigens, some of which have known uses: > [@](#): > > Other blood type systems exist to describe the presence or absence of other antigens. Diego positive blood is found only among East Asians and Native Americans. MNS systems gives blood types of M, N, and MN. It has use in tests of maternity or paternity. Duffy negative blood gives partial immunity to malaria. The Lutheran system describes a set of 21 antigens. Other systems include Colton, Hh or Bombay, Kell, Kidd, Lewis, Landsteiner-Wiener, P, Yt or Cartwright, XG, Scianna, Dombrock, Chido/Rodgers, Kx, Gerbich, Cromer, Knops, Indian, Ok, Raph, and JMH. ---
**Author:** ![smiling\_bandit](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@smiling\_bandit](https://boards.straightdope.com/u/smiling_bandit)\ **Post date:** [May 17, 2004, 8:58pm UTC](https://boards.straightdope.com/t/help-me-understand-blood-types-please/245610/6 "2004-05-17T20:58:31Z")
I’ve also heard there are some extremely rare blood types based on rare mutations. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [May 17, 2004, 9:55pm UTC](https://boards.straightdope.com/t/help-me-understand-blood-types-please/245610/7 "2004-05-17T21:55:37Z")
> [@smiling bandit](#): > > I’ve also heard there are some extremely rare blood types based on rare mutations. Sure there are. But, since they’re rare, they’re very rarely important. ---
**Author:** ![FilmGeek](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@FilmGeek](https://boards.straightdope.com/u/FilmGeek)\ **Post date:** [May 17, 2004, 10:45pm UTC](https://boards.straightdope.com/t/help-me-understand-blood-types-please/245610/8 "2004-05-17T22:45:37Z")
There was a diet fad for a while recently that was based on blood type. Seems like bunk to me, but what do I know? ---
**Author:** ![ZaLucky1](https://avatars.discourse-cdn.com/v4/letter/z/4af34b/32.png) [@ZaLucky1](https://boards.straightdope.com/u/ZaLucky1)\ **Post date:** [May 18, 2004, 12:23am UTC](https://boards.straightdope.com/t/help-me-understand-blood-types-please/245610/9 "2004-05-18T00:23:14Z")
> [@CURIOUS\_GEORGIE7](#): > > It’s been a while since i’ve taken an anatomy class and now I can’t remember all of the blood types and the order in which they were most common to the least common. > > Also, what effect, if any, does a particular blood type have on a person? > > For example, a friend was telling me that people with Type A blood have a higher likelihood of certain food allergies such as tomatoes. Is this even remotely true? > > I’m so confused! 😕 > > Thanks! This is what I have found as far as blood types and rareness … [Rare Blood Types - BloodBook, Blood Information for Life](http://www.bloodbook.com/rare.html) and blood type vs. your chances of having a food allergy related to it … [http://xtramsn.co.nz/health/0,,8158-1922459,00.html](http://xtramsn.co.nz/health/0,,8158-1922459,00.html) Now, my blood type is pretty yucky. I have O-. This means that if I need to get a blood transfusion for any reason, I can only receive O-. Pretty rare and unfair … a website to back me up - [Blood Type Facts - BloodBook, Information on Blood Type Facts for Life](http://www.bloodbook.com/type-facts.html) Hope this helps ---
**Author:** ![Thaumaturge](https://avatars.discourse-cdn.com/v4/letter/t/858c86/32.png) [@Thaumaturge](https://boards.straightdope.com/u/Thaumaturge)\ **Post date:** [May 18, 2004, 12:40am UTC](https://boards.straightdope.com/t/help-me-understand-blood-types-please/245610/10 "2004-05-18T00:40:12Z")
Not to worry **ZaLucky1** (this seems a misnomer in light of this thread 😛 ), there has been much progress made lately with blood substitutes. In 5 years I doubt they’ll give people whole blood for anything other than long term illnesses, since with a substitute there is no chance of disease.